1. Field of the Invention
The present invention relates to a newtype of muffling panel capable of damping and absorbing sound in low to medium sound ranges. More specifically, the present invention relates to a muffling panel of lightweight construction having a function of effectively excluding at a high level a sound in low sound and medium sound ranges in particular, which is useful in the walls and floors of buildings, sound absorbing walls in hallways, sound insulating walls along railroad tracks/expressways, soundproofing walls for machinery and engine rooms, and noise eliminators (mufflers) for internal combustion engines and the like.
2. Description of the Related Art
In general, thick walls made of a material with a large mass are required to isolate low sounds, and low and medium sounds of high sound volume, and up to this time, concrete walls, as well as steel, aluminum and other metal walls provided on the inside thereof with sound absorbing materials have often been used. However, walls of so-called heavy construction such as this type of walls are costly to manufacture, and also require considerable time and efforts to construct the same. Further, in the past, some attempts were also made to isolate sound by using a electrically produced reverse-phase sound, but this approach has drawbacks, such as problems of electric power to be consumed proportional to sound volume, complicated equipment to be constructed, and high costs for manufacturing thereof, and therefore, it never achieved widespread general use.
Under these circumstances, the present inventor, as a result of cumulative diligent research, having as an object the development of a new-type muffling panel of lightweight construction, having a simple construction, being inexpensive to manufacture, and having excellent muffling and sound-absorbing properties across a wide frequency band area, and being capable of effectively isolating sound in low sound and medium sound ranges in particular, has completed the present invention by successfully developing the below-described muffling panel of a completely new construction.